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United States

Lower Santa Ana River Mainstream Reach 9 Phase 5B

Reach 9 is located in the Santa Ana River (SAR) watershed within Orange and Riverside counties. Reach 9 is approximately 8.3 miles long, ranges in width between approximately 400 and 2,000 feet, and parallels SR-91 beginning at the Prado Dam outlet in Riverside County, downstream to the vicinity of the South Weir Canyon Road/Yorba Linda Boulevard Bridge in the City of Yorba Linda, Orange County. At that point, the SAR transitions from a relatively natural channel to an engineered channel that conveys flows to the Pacific Ocean.  

The $25 million Lower Santa Ana River Reach 9 Phase 5B awarded to OHLA extends from Phase 5A upstream approximately 3 miles towards the east end of Archstone Yorba Linda housing complex. The project consists of construction of a 24-inch grouted stone revetment, reinforced concrete outlet structures, existing side drain extension, bike path and operation and maintenance roads. The project goal is to improve the river banks to protect the homes and businesses from erosion and flooding due to future increased releases of flood waters from Prado Dam.  

The project is in a river bed, and downstream from a dam, requiring preparation of a flood evacuation plan just in case of a water release from the dam. Also, project sequencing called for rerouting of a bike path. 


Main Features: 

  • Slope protection with rip rap and grouted stone 

  • Bike path  

  • Riding/hiking trails 

  • Access ramps and maintenance roads 

  • RCP pipes